The present invention relates to an apparatus for measuring alignment of vehicle wheels, particularly, though not exclusively, of bicycles.
In a chain driven motor cycle, it is essential that the rear axle sprocket be aligned with the gearbox output sprocket. It is also desirable to be able to check front to rear wheel alignment when the front wheel is steered straight ahead.
The object of the present invention is to provide an apparatus with which these alignments can be checked with reference to the rear forks/swinging arm pivot, i.e. the axis about which the rear suspension link carrying the rear wheel is pivoted in the frame of the motor cycle.
According to the invention there is provided an apparatus for measuring vehicle wheel alignment comprising:
a yoke having a pair of aligned center pins engageable with a transverse axis in the vehicle
a collimated beam projector connectable to the yoke and adapted to project its beam at right angles to the axis of the center pins, and longitudinally of the vehicle with reference to the transverse axis and
a target for the beam so attachable to a wheel of the vehicle that alignment of the wheel can be measured.
It can be envisaged that the target is a reflector, having a mirror or the like arranged at right angles to the wheel, that is parallel to the axis of the wheel, for reflecting the beam back to the projector. When the wheel is aligned correctly the beam is reflected back along its projection plane. To detect this the projector can be provided with a transverse scale.
However, the preferred embodiment is simpler in that the target includes means for visualizing whether the projected beam is passing the parallel with the wheel. Conventionally, the visualization means comprise a set of scale lines on a plate having abutments adapted to cause the lines to be parallel to the wheel. The plate can be clamped to or hung on the wheel.
Preferably, the yoke is symmetric whereby the projector can be mounted on either side thereof, for projection of the beam along either side of the vehicle, for measurement on either side.
Further, the means of connecting the projector onto the yoke is preferably adapted to reverse the direction of projection of the beam for alignment measurement of both a front wheel and a rear wheel.